The present invention relates to a thin film patterning method and a method for manufacturing a liquid crystal display device, and in particular, to a thin film patterning method in which a composite layer structure having two different patterns is formed with a single mask, and a method for manufacturing a liquid crystal display device using the thin film patterning method.
Microelectronic technology is a new technology that develops along with integrated circuits, especially ULSI (ultra-large-scale integrated circuit). Microelectronic technology comprises a set of specialized technologies comprising system circuit designs, thin film patterning methods, materials preparation, automatic testing and packaging, and assembling etc. As microelectronic technology develops, its application expands gradually to manufacturing of other precision devices, such as a liquid crystal display device.
In microelectronic technology, a thin film is typically formed by sputtering, chemical vapor deposition or coating. The thin film is then patterned by a photolithograph process. The above two steps can be repeated to form an electronic component composed of multiple layers of thin films.
A conventional photolithograph process comprises following steps: applying a photoresist (PR) layer on a thin film; exposing and developing the photoresist layer with a mask so as to form a pattern in the photoresist layer; etching the thin film in accordance with the pattern in the photoresist layer to form a pattern in the thin film.
However, the mask used in the photolithograph process is expensive, and therefore the number of the masks used in the process has a significant influence on the manufacturing cost of an electronic component. In order to reduce cost, thin film patterning methods in which patterns are simultaneously formed in two different layers of thin films by using a single mask are proposed, such as a thin film patterning method using a dual-tone mask and a thin film patterning method using a lift-off process.
The thin film patterning method using a dual-tone mask comprises following steps: depositing a first thin film and a second thin film successively on a substrate; applying a photoresist layer on the second thin film, and exposing and developing the photoresist layer by using the dual-tone mask to form a photoresist pattern layer; etching the first and second thin film exposed by the photoresist pattern layer; removing a part of the photoresist pattern layer by ashing; etching the first and second thin film again exposed by the photoresist pattern layer; and stripping the photoresist pattern layer.
The thin film patterning method using a lift-off process comprises following steps: depositing a first thin film on a substrate; applying a photoresist layer on the first thin film, and exposing the photoresist layer by using a mask to form a photoresist layer; etching the first thin film exposed by the photoresist pattern layer; depositing a second thin film on the photoresist pattern layer and the substrate; and stripping the photoresist pattern layer along with the second thin film formed thereon by using the lift-off process.
With the thin film patterning method using the dual-tone mask, a region only with the second thin film can not be formed.
With the thin film patterning method using the lift-off process, a region in which the first and the second thin film overlaps as well as a region in which both of the first film and the second thin film are removed can not be formed.